Emergency Autoland Braking System

The disclosed embodiments relate generally to the field of autonomous vehicle control. More specifically, the disclosed embodiments are related to automatic braking for emergency autoland systems in aircraft.

Emergency autoland braking systems for aircraft have been described in the past. They generally use actuators acting directly on additional hydraulic master cylinders in the braking system. U.S. Pat. No. 10,442,529 to Dupre et al. discloses a system for controlling a lateral trajectory of an aircraft and includes actuators connected to the rudder pedals; however, the actuators described are used for providing haptic feedback to the pilot. U.S. Pat. No. 9,227,608 to Hill et al. discloses a decentralized electric brake system, known as brake-by-wire, and includes electric actuators used to actuate the mechanical braking system at the aircraft brake assembly. U.S. Pat. No. 9,656,641 to Griffith et al. discloses an aircraft electrical brake control system, known as brake-by-wire, and includes electric actuators used to actuate the mechanical braking system at the aircraft brake assembly.

In embodiments of the present disclosure, an aircraft braking system, includes a left brake cable operatively coupled to a braking mechanism and a left rudder pedal; a right brake cable operatively coupled to the braking mechanism and a right rudder pedal; a slider configured on a slide and mechanically coupled to the left brake cable and the right brake cable, wherein the slider is configured to displace the left and right brake cables when the slider is moved; and an actuator configured to displace the slider thereby activating the left and right braking mechanisms, respectively, wherein the actuator and the slider operate independently of the left and right rudder pedals.

In embodiments of the present disclosure, an emergency autoland braking system for aircraft includes: a pair of braking mechanisms; a pair of brake cables operatively coupled to the pair of braking mechanisms, respectively; a first braking subsystem configured to pull the pair of brake cables for activating the pair of braking mechanisms; and a second braking subsystem configured to pull the pair of brake cables for activating the pair of braking mechanisms, wherein the first and second braking subsystems operate independently of one another, and wherein the second braking system pulls the brake cables between the first braking subsystem and the pair of braking mechanisms.

In embodiments of the present disclosure, an emergency autoland braking system includes: an actuator configured to displace a left and right brake cable when the actuator is driven, wherein displacement of the brake cables engages a set of aircraft brakes; a calibration mechanism configured to adjust a magnitude of displacement of each brake cable when the actuator is driven; and a control system configured to engage the actuator such that the set of aircraft brakes is engaged based on instructions provided by the control system.

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Other aspects and advantages will be apparent from the following detailed description of the embodiments and the accompanying drawing figures.

The drawing figures do not limit the invention to the specific embodiments disclosed and described herein. The drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the invention.

The following detailed description references the accompanying drawings that illustrate specific embodiments in which the invention can be practiced. The embodiments are intended to describe aspects of the invention in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments can be utilized and changes can be made without departing from the scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense. The scope of the invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.

In this description, references to “one embodiment,” “an embodiment,” or “embodiments” mean that the feature or features being referred to are included in at least one embodiment of the technology. Separate references to “one embodiment,” “an embodiment,” or “embodiments” in this description do not necessarily refer to the same embodiment and are also not mutually exclusive unless so stated and/or except as will be readily apparent to those skilled in the art from the description. For example, a feature, structure, act, etc., described in one embodiment may also be included in other embodiments, but is not necessarily included. Thus, the technology can include a variety of combinations and/or integrations of the embodiments described herein.

Emergency autoland systems in some high-performance aircraft use automatic braking during the landing phase to stop the aircraft on the runway. For aircraft that do not have brake-by-wire systems, a mechanical input is required to engage wheel braking mechanisms (e.g., brake metering valves or master cylinders). When the system design is used on multiple aircraft, in which the different aircraft have different design aspects, actuating the rudder pedals using one actuator minimizes differences in design. Limiting the number of actuators may also be advantageous in reducing the system's complexity.

Where differential braking is not required, a single actuator may be used with a rigging calibration mechanism that may be configured to apply equal braking pressure to the left and right brake wheels. In such an embodiment, a pair of brake cables may be equally displaced by components of the rigging calibration mechanism. The command to the actuator from the emergency autoland system may be a simple discrete signal or a proportional command signal, based on the needs of the aircraft.

Embodiments disclosed herein use one mechanical actuator to physically engage the brake metering valve on aircraft that are equipped with electrohydraulic brake systems. The actuator engages wheel brakes downstream of the rudder pedals to provide braking in the same manner as the pilot (i.e., by pressing down on the top of the rudder pedals via “toe brakes” to activate wheel braking mechanisms). Where no differential braking is required, a brake pressure equalization means is provided so that a single actuator provides equal braking to the left and right wheels. A control system may send a signal to the actuator to engage the braking mechanism but does not interfere with the normal pilot usage when the actuator is unused. The control system can be configured with instructions (such as software) to send a simple discrete signal to the actuator if an anti-skid mechanism is implemented on the aircraft brakes, or the control system can send a signal configured to operate the actuator at a constant speed, or the control system may send another type of signal to engage the actuator. The nature of the signal may be informed by data from aircraft avionics in embodiments. The disclosed embodiments allow for any electromechanical actuators or servos required for the braking system to be installed in more spacious areas of the aircraft and also require less input force than direct brake pedal actuation methods.

Embodiments disclosed herein utilize a servo motor or electromechanical actuator (EMA) to apply force to the aircraft braking mechanism (e.g., the brake metering valve). This force may be applied to the braking mechanism directly via input levers or indirectly via input sectors or cables. An example of the force being applied directly via input levers is described in U.S. Provisional Patent Application No. 63/625,335 entitled Emergency Autoland Braking System and filed on Jan. 26, 2024, the disclosure of which is hereby incorporated by reference in its entirety. In the present application, the force is applied indirectly via input sectors or cables as further described below. Whether the force is applied to the braking mechanism inputs directly or indirectly, a centering mechanism is attached to the single actuator and used to equalize the force applied to the left and right inputs. Electrical power is applied to the servo or EMA such that the actuator may be engaged at full speed or at a controlled speed. The actuator engages the braking mechanism inputs sufficiently to provide the required braking up to a maximum braking force with anti-skid engagement.

Embodiments disclosed herein may be operated open loop or closed loop based on the specific implementation. For example, open loop operation may apply maximum braking force to intentionally engage an anti-skid system, allowing the anti-skid system to fully decelerate and stop the aircraft. One example of closed loop operation may be a system that applies a proportional braking force based on input from various sensors on the aircraft, including sensors for wheel speed, longitudinal acceleration, airspeed, altitude, etc. Based on feedback from one or more sensors, a braking force may be applied that slows the aircraft as quickly and safely as possible without skidding the tires. The system may also be implemented using any other method of mechanical force/torque transmission to the brake pedals, such as pushrods.

Referring now to, an autoland braking systemis configured as a subsystem of a braking system, in an embodiment. An aircraftcomprises braking systemto operate brakes on aircraft; however, aircraftis not shown inso that the features of braking systemmay be more clearly demonstrated. Autoland braking systemand rudder pedals (not shown) are subsystems of braking systemconfigured to engage any brakes mechanically coupled to braking system. Autoland braking systemand the rudder pedals may engage the brakes independently while either subsystem is currently engaging the brakes.

Braking systemcomprises at least braking mechanismand brake cablesL,R. “Upstream” indicates a direction toward the brake rudder pedals while “downstream” indicates a direction towards braking mechanism. Brake cablesL,R are a set of left and right brake cables operatively coupled to the pilot and copilot rudder pedals upstream (not shown) and braking mechanismdownstream. Brake cablesL,R are held under tension between the rudder pedals and brake mechanism. When a force pulls brake cablesL,R upstream, brake cablesL,R transmit that force to brake mechanism. For instance, a depression of the rudder pedals imparts an upstream force on brake cablesL,R, thereby engaging brake mechanism(via the mechanical linkage described in). When brake mechanismis engaged, aircraft brakes of aircraftapply a braking force.

When no upstream force is applied, braking systemis in a rest position. In the rest position, brake cablesL,R remain under tension but do not engage braking mechanism. Tie membersL,R hold brake cablesL,R under tension downstream, and the rudder pedals hold brake cablesL,R under tension upstream. A pulley bracketmounted to aircraftcomprises cable pulleysL,R, and cable pulleysL,R are configured to position brake cablesL,R parallel to one another upstream of braking mechanismand local to autoland braking system. Brake cablesL,R are considered to run in a longitudinal direction with respect to aircraft, and subsequent references to a longitudinal direction (e.g. “longitudinal,” “longitudinally”) indicate this same direction unless otherwise noted, and items described as running, traveling, or similar in the longitudinal direction may be assumed to be parallel unless otherwise noted.

A plurality of fairlead bracketsreceive brake cablesL,R in the longitudinal direction such that brake cablesL,R remain parallel in an area local to autoland braking system, particularly in a parallel regionshown innear a sliderand an actuator, which autoland braking systemcomprises and are further discussed in. Each fairlead bracketcomprises a pair of fairleadsL,R, wherein each fairleadL,R comprises a ring which receives a brake cable. Fairlead bracketmay comprise a nylon or plastic component configured to house portions of brake cablesL,R without causing wear of brake cablesL,R and mounted to portions of aircraftsuch as a frame, stringer, spar, or other structural component. Brake cablesL,R may slide freely in a longitudinal direction through fairleadsL,R, respectively. Left brake cableL runs through fairleadL and right brake cableR runs through fairleadR. The distance between fairleadsL,R on each fairlead bracketis the same, and each fairlead bracketmay be identical such that brake cablesL,R remain longitudinal and parallel within a parallel regionbetween any two fairlead brackets(i.e., in the area local to and adjacent the autoland braking system). In embodiments, a plurality of fairlead bracketsmay be configured to fairlead brake cablesL,R along the length of aircraftsuch that brake cablesL,R run in the longitudinal direction and remain substantially parallel adjacent to autoland braking system.

As seen in, a mechanical linkageis configured to transmit force from brake cablesL,R to braking mechanism. Specifically, tie membersL,R are configured to hold the downstream ends of brake cablesL,R respectively under tension. Tie membersL,R are mechanically coupled to lever armsL,R on pivotsL,R. Tie membersL,R are free to rotate on pivotsL,R. Lever armsL,R are rigidly fixed to extending members or other rotational means housed within shroudsL,R respectively such that armsL,R transmit torque to leversL,R. LeversL,R then act on components housed within mechanism. The specific action performed by leversL,R (e.g., a pull or rotation) may depend on the specific components configured within braking mechanismto engage brakes of aircraft. For instance, leversL,R may be a part of a metering valve assembly, and a torque applied to lever armL may engage a brake metering valve (not shown) within braking mechanism.

Brake mechanismmay comprise an electrohydraulic braking system wherein dual metering valves are configured to engage a left and right set of brakes respectively. A plurality of metering valves may also be used to engage a plurality of brakes, such as a set of front and rear brakes, or one or more master cylinders may be configured within braking mechanismto engage the brakes when acted on by a torque.

Referring now to, autoland braking systemis mounted to the frame of aircraftvia fasteners such as screws, bolts, welds, or other mounting methods.depicts portions of the frame of aircraftto demonstrate a possible placement of autoland braking systemwithin an aircraft while all subsequent figures do not depict the frame of aircraft. Autoland braking systemcomprises at least slider, brake cablesL,R, and an actuator, and is suitable for engaging the brakes on aircraftdownstream of the brake rudder pedals, as further described below. Autoland braking systemis configured to provide emergency braking to an aircraft independent of pilot or copilot actuation of the rudder pedals. As depicted in, autoland braking systemis in a rest position with no emergency braking features active. When activated, actuatorpulls sliderlongitudinally upstream.

Brake cables comprise claddingL,R and ball endsL andR. CladdingL,R comprises a stiffened portion of brake cablesL,R configured to eliminate freeplay in the braking system under low tension. Furthermore, brake cablesL,R are approximately parallel to one another near sliderand travel in the longitudinal direction. Ball endsL,R are components fixed to brake cablesL,R that provide a region of locally increased diameter for brake cablesL,R, such that a force can be applied to brake cablesL,R in the longitudinal direction by pressing on ball endsL,R. For instance, ball endsL,R allow for a force to be applied parallel to the direction of brake cablesL,R.

During normal aircraft operation with no emergency autoland activated, a pilot or copilot may depress the rudder brake pedals of aircraftto engage the brakes. Force from the pedals is applied upstream of slider, such as by rudder pedals or toe brakes.

Slideris configured as a rigging calibration mechanism that may apply a force to brake cablesL,R when acted on by a single actuator, such as actuator. Slideris secured relative to aircraftby two-hole washerand slide. Two-hole washercomprises a plastic washer configured to accept two bolts that is bolted into slidevia shoulder boltswith a shoulder boltslotted into each of slotsandof slider, as seen most clearly in. Slideis a smooth surface configured to allow sliderto slide in a linear direction, particularly the longitudinal direction. Slotsandare linear slots that permit sliderto move in the longitudinal direction. The use of two slots prevents the rotation of slideraround either shoulder boltand two-hole washerconstrains slidersuch that slideris constrained to move linearly in the longitudinal direction.

In a rest position, autoland braking systemis not engaged and does not cause braking. Slidermay contact components of brake cablesL,R but does not supply an additional force to brake cablesL,R beyond the resting tension of the system. Actuatoris not engaged and thus does not drive sliderin the rest position. Autoland braking systemis demonstrated in an engaged position in.

Sliderfurther comprises mounting loopsL,R, adjustment tubesL,R, jam nutsL,R, and fairlead retainersL,R. Adjustment tubeL is a hollow cylinder screwed into mounting loopL suitable for housing and enclosing a portion of brake cableL. In embodiments, adjustment tubeL comprises external threading or another means of securing adjustment tubeL within mounting loopL while allowing for the longitudinal position of adjustment tubeL to be adjusted relative to slider. Jam nutL is configured to lock adjustment tubeL in its position in the longitudinal direction, as further discussed in connection with. Adjustment tubeL envelops brake cableL: one end of adjustment tubeL is open such that brake cableL may pass through adjustment tubeL. The other end comprises fairlead retainerL, which in embodiments comprises two fairlead halves configured to allow brake cableL to pass through in the longitudinal direction. Fairlead retainerL contacts ball endL when the brakes are not depressed. Brake cableL runs longitudinally through adjustment tubeL, and thus is partially encased by adjustment tubeL.

In the rest position, ball endL rests against or sits next to fairlead retainerL. Thus, if slidermoves upstream, such as if driven by actuator, fairlead retainerL will press against ball endL. Because ball endL is not free to slide along brake cableL, brake cableL will be pulled as slideris pulled by actuator. Likewise, the same mechanism is used when fairlead retainerR presses against ball endR of brake cableR, and therefore the description is not repeated accordingly. Because the same mechanism applies to both brake cablesL,R, and because sliderpushes the parallel brake cables in only the longitudinal direction, slideruniformly displaces brake cablesL,R.

When autoland braking systemis engaged, sliderwill always impart an equal force on both brake cablesL,R if neither brake cable is acted on by the rudder pedals. While balancing member applies a force to ball endsL,R, but upstream braking is not at a maximum, the brake pedals may still be depressed. Thus, because the rudder pedals may operate independently of autoland braking system, a pilot or copilot may provide additional braking to either brake cablesL,R by depressing a pedal even if autoland braking systemis active. This requires a greater braking force from the toe brakes of the rudder pedals than from actuatorgiven that a braking force is already applied to brake cablesL,R. This system allows for an uneven braking force to be applied to the brakes in the event that both autoland braking systemand the rudder pedals are engaged, as a single rudder pedal may engage only a single brake cableL,R even if autoland braking systemis active. Actuatoris operatively coupled to a noseA of sliderat a joint. Actuatorcomprises an electromechanical actuator, a servo motor, a pushrod, or another device configured to apply mechanical force in the longitudinal direction. The power supplied to actuatoris such that the speed at which actuatoroperates is controlled and may be a constant speed determined by a control system. In embodiments, a control system may send a discrete signal to actuatorsuch that actuatoris moved at a constant speed. In other embodiments, actuatormay be configured to operate at a variable speed, by a plurality of signals, or by a continuous signal. Autopilot or an emergency autoland control system on aircraftmay operate emergency autoland features on the aircraft, including but not limited to executing instructions to engage autoland braking systemwith actuatordriven at a speed determined by the emergency autoland control system. This system may be implemented by a controller comprising software installed in a non-volatile memory of a computer on aircraft. In embodiments, the system may comprise a simple discrete signal or proportional command signal directed to actuator.

In simple discrete control, which may comprise an open-loop system, the controller supplies full power to actuatorvia a simple discrete signal or otherwise to automatically engage an anti-skid mechanism configured on the brakes of aircraft. In this implementation, the braking force may be applied indefinitely or until the emergency autoland control system powers down.

For proportional control, the controller may apply a proportional braking force based on aircraft sensor readings for wheel speed, longitudinal acceleration, airspeed, altitude, or other data. The force applied by actuatormay be such that sliderengages braking mechanismbut does not cause lockup, skid, or a destabilization of aircraft. This control system would be implemented as a closed-loop system wherein feedback arises as the aircraft decelerates, leading to different conditions registered by aircraft sensors. In embodiments, an electrical signal of varying output may be sent to actuatorto produce a power output and level of actuation of corresponding varying output.

In embodiments, actuatorcomprises a screwwhich secures mounting loopto joint. In the rest position, retractable portionof actuatoris extended outward from actuator. When actuatorengages, actuatorpulls retractable portioninto actuator, thereby driving sliderlongitudinally upstream and applying a force to brake cablesL,R. Actuatorand retractable portionare aligned along an axis parallel to brake cablesL,R, such that the direction of the applied force is parallel to both brake cablesL,R.

Actuatoris secured to aircraftvia a jointand fairlead bracket. Jointcomprises a joint with a bolt or screw that permits actuatorto be mounted at an angle relative to aircraftto conserve space. Fairlead bracketcomprises a metal support that secures actuatorrelative to aircraft. Actuatoris mounted downstream of the rudder pedals such that autoland braking systemdoes not occupy space in the cockpit of aircraft.

provides a cross-sectional view of adjustment tubeR. Adjustment of adjustment tubesL,R allows for a rigging calibration of autoland braking system, wherein the displacement of brake cablesL,R caused by autoland braking systemmay be increased or decreased for each brake cable to produce an equal brake pressure or amount of braking supplied to each brake when brake cablesL,R are displaced by autoland braking system. Within adjustment tubeR, brake cableR runs parallel to slider. Ball endR of brake cableR rests against fairlead retainerR.

Fairlead retainerR may comprise aluminum or another durable material suitable for applying pressure to ball endR. Fairlead retainerR is secured to adjustment tubeR by a plurality of cotter pins, but in alternate embodiments may be secured to adjustment tubeR by other means such as glue or a threaded coupling. Brake cableR is enveloped by fairlead halvesR within adjustment tubeL such that fairlead halvesR provide a barrier between adjustment tubeR and brake cableR. Fairlead halvesR may comprise plastic, nylon, or another material suitable for preventing brake cable wear should brake cableR contact a fairlead halfR. In embodiments, two or more fairlead halvesR may be configured within adjustment tubeR. Adjustment tubeL comprises fairlead halvesL (not shown), fairlead retainerR, and cotter pinsconfigured in a similar manner and their description is not repeated accordingly.

Adjustment tubeR comprises exterior threads configured to align with threading within mounting loopR to provide a threaded coupling. In embodiments, adjustment tubeR may be repositioned by rotating adjustment tubeR within mounting loopR such that fairlead retainerR at the end of adjustment tubeR lies further forward or aft in the rest position. Once a desired position of adjustment tubeR is reached, jam nutR may be screwed on adjustment tubeR to lock adjustment tubeR in place relative to slider.

The positioning of each adjustment tubeL,R may comprise a calibration of autoland braking system, wherein autoland braking systemis calibrated to engage each brake by displacing brake cablesL,R when actuatorapplies a maximum force to slider. In embodiments, the position of the adjustment tubesL,R may be set to displace each of brake cablesL,R equally such that a set of aircraft brakes are equally engaged for balanced braking. This may comprise an equal positioning of each adjustment tubeL,R relative to slider. An asymmetrical positioning may be preferred to meet manufacturing tolerances in the cable assembly. For instance, in embodiments, in a default position, adjustment tubeR is positioned as forward or upstream as possible relative to slider, and in this position, fairlead retainerR contacts ball endR. From this position, adjustment tubeR may be moved aft or downstream relative to brake cableR and sliderby rotating adjustment tubeR. This moves fairlead retainerR out of contact with ball endR, such that more displacement of slideris required before autoland braking systemengages the brakes connected to brake cableR. When adjustment tubeR is moved downstream, the magnitude of displacement imparted on brake cableR via pressure applied by fairlead retainerR is reduced given that fairlead retainerR remains static relative to sliderand sliderhas a range of motion limited by contact between slots,and shoulder bolts. Adjustment tubeR is therefore adjusted to calibrate a maximum displacement of brake cableL. Thus, autoland braking systemmay be calibrated to apply less brake pressure to systems that require less brake pressure.

For calibrating displacement of brake cableL, adjustment tubeL, mounting loopL, fairlead retainerL, and associated components are similarly arranged to their counterparts on left brake cableR, and their description is not repeated accordingly.

Autoland braking systemmay also be configured on multiple aircraft without the introduction of new components or removal of preexisting ones: only the positions of adjustment tubesL orR need be adjusted to make the brake pressure supplied by autoland braking systemsuitable for a given aircraft.

depicts autoland braking systemwhen autoland braking systemis not engaged but brakes upstream of autoland braking system(such as rudder pedals or toe brakes) are engaged. Brake cablesL,R have been displaced upstream, as seen by the positions of ball endsL,R. VectorsL,R demonstrate the direction of the displacement.

depicts autoland braking systemwhen autoland braking systemis engaged and supplies a greater braking force to the braking cables than any upstream braking subsystems. Slideris displaced to a maximum degree (as limited by the length of slots,) by actuator, and the direction of the displacement is demonstrated by vectorsL andR. Brake cablesL,R have been displaced upstream as fairlead retainersL,R apply a force to ball endsL,R.

Many different arrangements of the various components depicted, as well as components not shown, are possible without departing from the spirit and scope of what is claimed herein. Embodiments have been described with the intent to be illustrative rather than restrictive. Alternative embodiments will become apparent to those skilled in the art that do not depart from what is disclosed. A skilled artisan may develop alternative means of implementing the aforementioned improvements without departing from what is claimed.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations and are contemplated within the scope of the claims. Not all steps listed in the various figures need be carried out in the specific order described.